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How to Caulk Baseboards

This step-by-step guide will explain how to caulk baseboards in a way that creates neat edges and joints. There are also some tips for keeping things clean as you work. These steps apply to both paint and stain-grade baseboards installed against a painted surface.

by Tom Scalisi
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iStock

While caulking is one of the most important steps for creating a finished look, it’s not always the most fun. It can be very messy, and the results can be hit or miss. When it comes to crouching or kneeling to caulk baseboards, the margin for error is that much greater.

Steps for Caulking Baseboards:

1. Gather Your Tools

To keep things simple, gather everything before you start. Here’s a list of tools and materials you’ll need:

Don’t skip the knee protection. Even if you have healthy knees, kneeling will take a toll on them. If you aren’t comfortable, you won’t be able to focus on producing quality results.

2. Choose the Right Caulk

There are so many caulking compounds available that choosing the right one can seem overwhelming. You’ll need paintable caulk, so look for a product that has a latex base or clearly states that you can paint it.

Silicone-based caulks are great for tubs, toilets, and sinks, but they don’t usually take paint well.

3. Prepare Your Baseboards

  • Lots of dust, pet hair, and other undesirables land on baseboards, so be sure to vacuum them before starting. Corners can be particularly dirty, so get your old paintbrush out and dust the corners as best as possible.
  • This is also the time to check for any damage or nails sticking proud of the baseboard’s edge. Take a few minutes to make any repairs or sink any pesky nails with your hammer and nail set.
  • It’s best to fill holes like these with a wood filler, as they don’t shrink but do sand easily for a perfectly smooth surface.

4. Roll out the Painter’s Tape

  • Unless you’re working with stain-grade baseboards, this step isn’t necessary. In fact, it’s not always possible due to the profile of the baseboard, but it can be helpful.
  • If you choose to use tape, lay a strip along the top edge of your baseboard. Hold it back from the wall at least 1/8-inch to give the caulk some baseboard surface to cling to. You can also tape the wall in a similar fashion.
  • The tape helps to ensure a decent-quality job, but if you’re patient and handy with a caulk gun, you don’t need it.

5. Cut the Tip of the Tube

  • Before you can start caulking, you need to remove a bit of plastic from the end of the nozzle or tip of the caulking tube.
  • Using your utility knife, cut a small section from the end of the tip at a slight angle (45 degrees or less). The angle will allow you to tuck the nozzle into a corner, placing the caulk exactly where it needs to be.
  • Start with a small hole as you’ll be able to control your flow better and limit messes. You’ll also minimize the sloppy effects of an air bubble in the tube. If you find the caulking gun is just too hard to squeeze, cut a slightly bigger hole.
  • Some tubes have seals that need puncturing before you can use them. Most caulking guns have a wire “poker” underneath to do the job. You can also use a wire hanger if necessary.

6. Squeeze and Move

  • Start in a corner, but don’t tuck the nozzle all the way into it (this always creates a mess). Placing the nozzle on the baseboard’s top edge and against the wall, hold it back from that corner about 1/4-inch and start caulking. Be sure that you’re moving and squeezing at the same time. Using a smooth motion, work out from the corner toward the middle of the wall.
  • You don’t have to caulk the whole baseboard in one pass. Repeat the process from the opposite corner, allowing the beads of caulk to meet in the middle.
  • For bigger gaps, slow down and let more caulk flow into the void.

7. Clean It Up

  • Wet your rag and ring it out.
  • Wet your finger on the rag and then use the pad of your finger to smooth the bead of caulk along the top of the baseboard. Work your way out from the corners, allowing the smoothed beads to meet in the middle of the wall.
  • Use a bit of the excess on your finger to finish the small gap you left in the corner.
  • Be sure to keep your finger wet to avoid pulling the caulk out of the seam.
  • Since you cut a small hole in your tube, the less-is-more approach should keep messes to a minimum. Wipe your finger on the wet rag between passes.
  • If your paint-grade baseboards have quarter-round moldings, repeat steps five through seven to caulk them.

8. Caulk the Miters (Paint-Grade Trim Only)

  • The only areas left to caulk are the inside miters in the corners. Run a thin bead of caulk from the bottom edges of the miters to the tops.
  • Wet your finger and run it along the bead to press it into the corner.
  • If your miters have large gaps (it happens), don’t use your finger. Instead, use a putty knife to shape a perfectly square corner.
  • You can caulk outside miters, but wood filler works better. Use a putty knife to spread the wood filler in the gap, allow it to dry, and sand it smooth for a perfect outside miter.

9. Remove the Tape

  • If you used tape, now’s the time to remove it.
  • (If the caulk dries before you remove it, the tape can leave edges in your seam). Remove it, smooth any rough spots with a wet finger, and enjoy your nicely caulked baseboards.

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